Determine whether the sequence converges or diverges. If it converges, find the limit. (If an answer does not exist, enter DNE.) an = 4n cos(7nπ)

Respuesta :

Answer:

The sequence diverges.

Step-by-step explanation:

A sequence [tex]a_{n}[/tex] converges when [tex]\lim_{n \rightarrow \infty} a_{n}[/tex] is a real number.

In this question, the sequence given is:

[tex]a_{n} = 4n\cos{(7n\pi)}[/tex]

The cosine is always going to be between -1 and 1, so for the convergence of the sequence, we look it as: [tex]a_{n} = 4n[/tex]. So

[tex]\lim_{n \rightarrow \infty} a_{n} = \lim_{n \rightarrow \infty} 4n = \infty[/tex]

Since the limit is not a real number, the sequence diverges.